Lubricating composition



Patented May 3, 1938 UNITED STATES LUBRICATING COMPOSITION Floyd L.Miller and Carl Winning, Elizabeth, N. 1., assignors to Standard OilDevelopment Company, a corporation of Delaware No Drawing. ApplicationMay. 23, 1932,

Serial No. 613.132

24 Claims.

The present invention relates to improved lubricating oils and morespecifically tolubricating oils of low pour point and to methods forreducing cold test or pour point of such oils by the use of relativelysmall quantities of pour depressing agents. Our method will be fullyunderstood from the following description.

Hydrocarbon oils used for lubricating purposes frequently contain waxyconstituents which cause them to congeal at relatively elevatedtemperatures, say 30, 45, 60 or even at 75 F. or higher, depending onthe amount of waxy constituents present. Butfor the high congeaiingpoint these oils would be good liquid lubricants at temperaturesconsiderably therebelow and it is the practice in oil refining to removewax, or a suflicient amount thereof, .for the purposein hand. We havediscovered a class of substances, however, which may be added to oils inextremely small quantities and which in such quantities have the powerof so modifying the crystal form or crystal growth that the oil remainsliquid at temperatures far below their normal solidification or pourpoints. The materials which we contemplate in this connection are of thegeneral class of solubilized polysaccharides, that is to say, thepolysaccharides which have been rendered soluble in oily liquids andwhich comprise derivatives of cellulose, starch, sugar, dext'rin and thelike. It is not necessary that these materials be greatly soluble butonly to the extent of l or 2% and in some instances to even less. Thesolubilized products which we have particularly in mind are derivativesof the polysaccharides which contain hydrocarbon groups in' sutlicientquantity to bring about a solubility in oil to the degree indicatedabove. These hydrocarbon groups may be attached to the polysaccharide soas to form ethers or esters or similar compounds and are made by themeth- 40 ods now generally known in the art. The degree of solubility asindicated above depends to a great extent on the number and length ofthe hydro-v carbon chains and these are preferably straight chains,although branch chains and cycle groups are permissible. If chains ofmore than 8 or 10 carbon atoms, for example, preferably 10 to 22 carbonatoms, are attached to the cellulose molecule, for example, the materialbecomes relatively soluble and may be termed for our purposes freelysoluble, which is to say that it becomes soluble to the extent of atleast 2 or 3% and generally to even 10%. Where shorter chains are usedthe materials are progressively less soluble and may be so insolublethat they cannot be used at all for the purpose in hand. We prefer touse polysaccharide derivatives which are soluble to an extent of 2 to10% or more, and as stated above, these derivatives may be esters,ethers or some similar derivatives. The hydrocarbon chains shouldcontain at least 8 or 10, preferably 10 5 carbon atoms, and the numberof chains should be such as to bring the total number ofcarbon atoms inthe hydrocarbon radicals to 20 or more. The carbon atoms of the chainwhich are attached only to carbon or hydrogen may be termed the 10carbon atoms of the hydrocarbon group.

For our purposes the esters have been indicated as suflicient and thecellulose or other esters of organic acids such as 'stearic 'acid, oleicacid, erucic or behenic and the like may be used. But 15 the lower acidssuch as lauric and the like are also entirely suitable though where twostearyl groups suffice, 3 lauric groups are desirable to give thedesired solubility. synthetically produced acids,

for example produced by the oxidation of paraflin 20 wax or ceresin or,of hydrocarbon oils with air or other oxidizing agents such as nitricacid or similar substances may be used. Mixtures of these syntheticacids may serve our purpose and these acids may be used in connectionwith the natural acids as indicated above. 01 the ester derivatives themono-, di-, or tri-acid esters are all suitable, although it ispreferable to use a tri-ester in order to obtain greater solubility. Ofthe ethers' it is preferable to use those which are 30 soluble to thesame extent as theacids used above and the ethers of decyl alcohol, ortetradecyl, cetyl and the like may be used although these are givenmerely as examples. The ethers, in fact, may be made from any of thehigher halides, for 35 example containing more than 8 or 10 carbonatoms, and as i diated in connection with the acid radicals hy rocarbonderivatives should contain enough groups to provide at least 20 andpreferably more carbon atoms in the hydrocarbon to groups. 1 f

The amount of these solubilized polysaccharides to be used for ourpurpose is, of course, of considerable importance and generallytheamount will be less than 2% by weight. It is preferred to 45 use inthe neighborhood of /g to 1% and we have observed that there is a fairlywell defined optimum quantity for pour inhibition. If large amounts beused the oil is considerably thickened and the pour ,point'is not so lowas might be 50 obtained with the optimum quantity. We prefer to use theagents in such small amounts that the thickening caused by solution ofthese materials is slight but in some instances the thickening will beappreciable. In general we prefer to'use the 55 that is to say, inproportions suitable for pour inhibiting without causing substantialthickening.

V *The agents which we prefer among the polyiii) saccharide derivativesare those of cellulose because they are cheaper and more effective thanthe other substances, but sugar, starch, dextrin and the like aresuitable and give substantially similar effects. There may be somedifllculty in dissolving these substances even through they may havebeen termed freely soluble, but generally heating to 300 or 350 inpresence of the oil is sufficient to cause the material to go intosolution. The entire quantity of the agent should be dissolved and theoil should be both clear and brightso that the appearance gives noindication of any addition agent whatever. A slight turbidity may not.be objectionable but we prefer to produce-perfectly clear oils and theslight excess over what is clearly soluble should be removed. Theseagents do not in any way decrease the value of the oils as lubricants orchange the properties such as flash, color, carbon content'and the liketo any substantial extent.

As an example of the effect of such substances the following may betakenas illustrative:

An oil known as Manchester Spindle is selected with the followingspecification, but unblended:

Gravity 30. 5 Viscosity at 100 F. 148. 6 seconds Saybolt Viscosity at210 F..'. 42. 6 seconds Saybolt Flash 390 Color 11.0

Carbon 014% Pour point 30 F.

To such an oil cellulose trilaurate is added in small amounts from 0.1to 2% by weight and the properties of the 'oil are shown in thefollowing table:

Gravity an 30.5 30.5 30.5 30.5 va. 1oor 165 110 200 302 Vis.@2i0 F. 443.1 44.0 41.0 52.6 Pour point 5 -5 0 to- F. The other properties of theoil are substantially unchanged. These oils are .found to be perfectlystable and wholly satisfactory for the operations to which minerallubricating oils are ordinarily devoted.

Cellulose stearate or oleate or the naphthenate formed from naphthenicacids to be found naturally occurring in petroleum of the type obtainedin the Texas fields and also in the Russian or Rumanian fields aresuitable for our purposes, and the cellulose esters of acids obtained bythe oxidation of paraflin wax with air at temperatures from 100 to 160C. in the presence oi catalysts of the type of previously oxidizedparaffln, manganese, cobalt salts, organic acids, barium cinnamate andthe like may be used. The ethers of cellulose are also perfectlysatisfactory such as decyl cellulose, etc.

Our invention is not to be limited to any particular solubilizedpolysaccharides or to any method of making such substances, nor to anytheory or explanation of their eifect on waxcontaining oils, but only tothe claims in which we wish to claim all novelty inherent in theinvention.

We claim:

1. A composition of matter comprising a viscous waxy mineral oilcontaining an ether of cellulose soluble therein and in pour depressingproportions less than 2% by weight.

2. A composition according to claim 1 in which the hydrocarbon group ofthe cellulose ether is straight chained and contains at least 20 carbonatoms.

3. A composition according to claim 1 in which the hydrocarbon group ofthe cellulose ether contains a plurality of hydrocarbon radicalscontaining a total of at least 20 carbon atoms in the hydrocarbongroups.

4. A composition according to claim 1 in which an alkylated cellulose ispermanently soluble and present to the extent of .1 to 1%. 4

5. A composition of matter comprising a viscous mineral oil containingwax and a cellulose ester of stearic acid in pour depressing proportionsless than 2%- by weight.

6. A composition ofmatter comprising a viscous mineral oil containingwax and a soluble cellulose ester of an acid containing from 10 to 22carbon atoms and in pour inhibiting proportions less than 2% by weight.

'7. A composition of-matter according to claim 6 in which the acids areof the type produced by the low temperature oxidation of paraiiin wax.

8. A composition of matter according to claim 6 in which cellulosetrilaurate is used.

9. A composition of matter according to claim 6 in which the ester ispresent in proportion from 10. A composition of matter comprising aviscous waxy lubricating oil containing ,6 to 2% of an oil solublecellulose derivative selected from the class of ethers and esters.

11. A mineral oil composition containing wax in amount suflicient tocause the oil to have an undesirably high pour point, and a mineral oilsoluble poly-saccharide in amount less than 2% by weight of thecomposition and adapted to depress the pour point of the oil.

12. A mineral oil composition containing wax in amount suflicient tocause the oil to have an undesirably high pour point, and a mineral oilsoluble poly-saccharide derivative made .freely soluble in the oil bythe addition to the poly-saccharideof a hydrocarbon radicalto form acompound of the class of esters and ethers, said de-' rivative beingadded to the oll in pour depressing proportions less than 2% by weightof the composition.-

13. A mineral oil containing wax in amount sufficient to cause the oilto have an undesirably high pour point, and a' cellulose derivativecontaining a hydrocarbon radical added to the cellulose, such derivativebeing'freely soluble in the oil and present in proportions less than 2%by weight but suflicient to materially reduce the pour point.

14. A composition of matter comprising a-waxy cellulose derivative witha plurality of hvdrocarbon radicals containing a total of atleast 20carbon atoms in the hydrocarbon groups.

15. A composition of matter according to claim 13 comprising a viscousmineral oil containing wax and a cellulose ester soluble therein.

16. A composition of matter according to claim 13 comprising a viscousmineral oil containing wax and a cellulose ester soluble therein, suchester being derived from an organic acid containing at least 20 carbonatoms.

17. A composition of matter according to claim 13 comprisng a viscousmineral oil containing wax and a cellulose ester soluble therein, suchester produced by combination of a plurality of acidic groups with thecellulose and providing a total of at least 20 carbon atoms in suchacidic groups.

18. A lubricating oil containing wax in amount suiflcient to causetheoil to have an undesirably high pour point, and a small amount of asub.- stance selected from the class consisting of mineral oil solublepoly-saccharides and their derivatives, such amount being suificient tomate-.- rially reduce the pour point of the oil but insufflcient toincrease the Saybolt viscosity measured at 210 F. by more than 10seconds.

3 19. Composition according to claim 18 in which the poly-saccharidederivative is a soluble cellulose ester of an acid containing from 10-22carbon atoms.

20. Composition according to claim 18 in which the poly-saccharidederivative is a soluble cellulose ester of an acid produced by the lowtemperature oxidation of paramnwax.

21. A low pour point mineral oil composition comprising a wax containingmineral oil and a condensation product of sucrose and an aliphatic acidthe condensation product being present in relatively small amountssuflicient to cause a lowering of the pour point of the mineral oil.

22. The composition of claim 21, wherein the acid used is a fatty acid.

23. The composition of claim 21, wherein the acid used is stearic acid.

24. A low pour point mineral oil composition comprising a mineral oiland a condensation product of sucrose and an aliphatic acid thecondensation product being present in' relatively small amountssufiicient to cause a lowering of the pour point of the mineral oil.

FLOYD L. MILLER. CARL WINNING.

